diff --git a/lib/rscons.rb b/lib/rscons.rb
index 9a89dc9..cedbb18 100644
--- a/lib/rscons.rb
+++ b/lib/rscons.rb
@@ -19,6 +19,7 @@ require_relative "rscons/builders/simple_builder"
 
 # Namespace module for rscons classes
 module Rscons
+
   # Names of the default builders which will be added to all newly created
   # {Environment} objects.
   DEFAULT_BUILDERS = [
@@ -37,110 +38,114 @@ module Rscons
   # Class to represent a fatal error while building a target.
   class BuildError < RuntimeError; end
 
-  # Remove all generated files.
-  #
-  # @return [void]
-  def self.clean
-    cache = Cache.instance
-    # remove all built files
-    cache.targets.each do |target|
-      FileUtils.rm_f(target)
-    end
-    # remove all created directories if they are empty
-    cache.directories.sort {|a, b| b.size <=> a.size}.each do |directory|
-      next unless File.directory?(directory)
-      if (Dir.entries(directory) - ['.', '..']).empty?
-        Dir.rmdir(directory) rescue nil
+  class << self
+
+    # Remove all generated files.
+    #
+    # @return [void]
+    def clean
+      cache = Cache.instance
+      # remove all built files
+      cache.targets.each do |target|
+        FileUtils.rm_f(target)
       end
-    end
-    cache.clear
-  end
-
-  # Return whether the given path is an absolute filesystem path.
-  #
-  # @param path [String] the path to examine.
-  #
-  # @return [Boolean] Whether the given path is an absolute filesystem path.
-  def self.absolute_path?(path)
-    path =~ %r{^(/|\w:[\\/])}
-  end
-
-  # Return whether the given target is a phony target.
-  #
-  # @param target [Symbol, String] Target name.
-  #
-  # @return [Boolean] Whether the given target is a phony target.
-  def self.phony_target?(target)
-    target.is_a?(Symbol)
-  end
-
-  # Return a new path by changing the suffix in path to suffix.
-  #
-  # @param path [String] The path to alter.
-  # @param suffix [String] The new filename suffix, e.g. ".exe".
-  #
-  # @return [String] New path.
-  def self.set_suffix(path, suffix)
-    path.sub(/\.[^.]*$/, "") + suffix
-  end
-
-  # Return the system shell and arguments for executing a shell command.
-  #
-  # @return [Array<String>] The shell and flag.
-  def self.get_system_shell
-    @@shell ||=
-      begin
-        test_shell = lambda do |*args|
-          begin
-            "success" == IO.popen([*args, "echo success"]) do |io|
-              io.read.strip
-            end
-          rescue
-            false
-          end
+      # remove all created directories if they are empty
+      cache.directories.sort {|a, b| b.size <=> a.size}.each do |directory|
+        next unless File.directory?(directory)
+        if (Dir.entries(directory) - ['.', '..']).empty?
+          Dir.rmdir(directory) rescue nil
         end
-        if ENV["SHELL"] and ENV["SHELL"] != "" and test_shell[ENV["SHELL"], "-c"]
-          [ENV["SHELL"], "-c"]
-        elsif Object.const_get("RUBY_PLATFORM") =~ /mingw/
-          if test_shell["sh", "-c"]
-            # Using Rscons from MSYS should use MSYS's shell.
-            ["sh", "-c"]
+      end
+      cache.clear
+    end
+
+    # Return whether the given path is an absolute filesystem path.
+    #
+    # @param path [String] the path to examine.
+    #
+    # @return [Boolean] Whether the given path is an absolute filesystem path.
+    def absolute_path?(path)
+      path =~ %r{^(/|\w:[\\/])}
+    end
+
+    # Return whether the given target is a phony target.
+    #
+    # @param target [Symbol, String] Target name.
+    #
+    # @return [Boolean] Whether the given target is a phony target.
+    def phony_target?(target)
+      target.is_a?(Symbol)
+    end
+
+    # Return a new path by changing the suffix in path to suffix.
+    #
+    # @param path [String] The path to alter.
+    # @param suffix [String] The new filename suffix, e.g. ".exe".
+    #
+    # @return [String] New path.
+    def set_suffix(path, suffix)
+      path.sub(/\.[^.]*$/, "") + suffix
+    end
+
+    # Return the system shell and arguments for executing a shell command.
+    #
+    # @return [Array<String>] The shell and flag.
+    def get_system_shell
+      @@shell ||=
+        begin
+          test_shell = lambda do |*args|
+            begin
+              "success" == IO.popen([*args, "echo success"]) do |io|
+                io.read.strip
+              end
+            rescue
+              false
+            end
+          end
+          if ENV["SHELL"] and ENV["SHELL"] != "" and test_shell[ENV["SHELL"], "-c"]
+            [ENV["SHELL"], "-c"]
+          elsif Object.const_get("RUBY_PLATFORM") =~ /mingw/
+            if test_shell["sh", "-c"]
+              # Using Rscons from MSYS should use MSYS's shell.
+              ["sh", "-c"]
+            else
+              ["cmd", "/c"]
+            end
           else
-            ["cmd", "/c"]
+            ["sh", "-c"]
           end
-        else
-          ["sh", "-c"]
         end
-      end
-  end
+    end
 
-  # Return an Array containing a command used to execute commands.
-  #
-  # This will normally be an empty Array, but on Windows if Rscons detects
-  # that it is running in MSYS then ["env"] will be returned.
-  #
-  # @return [Array<String>] Command used to execute commands.
-  def self.command_executer
-    @@command_executer ||=
-      if Object.const_get("RUBY_PLATFORM") =~ /mingw/
-        if ENV.keys.find {|key| key =~ /MSYS/}
-          begin
-            if IO.popen(["env", "echo", "success"]) {|io| io.read.strip} == "success"
-              ["env"]
+    # Return an Array containing a command used to execute commands.
+    #
+    # This will normally be an empty Array, but on Windows if Rscons detects
+    # that it is running in MSYS then ["env"] will be returned.
+    #
+    # @return [Array<String>] Command used to execute commands.
+    def command_executer
+      @@command_executer ||=
+        if Object.const_get("RUBY_PLATFORM") =~ /mingw/
+          if ENV.keys.find {|key| key =~ /MSYS/}
+            begin
+              if IO.popen(["env", "echo", "success"]) {|io| io.read.strip} == "success"
+                ["env"]
+              end
+            rescue
             end
-          rescue
           end
-        end
-      end || []
-  end
+        end || []
+    end
+
+    # Set the command executer array.
+    #
+    # @param val [Array<String>] Command used to execute commands.
+    #
+    # @return [Array<String>] Command used to execute commands.
+    def command_executer=(val)
+      @@command_executer = val
+    end
 
-  # Set the command executer array.
-  #
-  # @param val [Array<String>] Command used to execute commands.
-  #
-  # @return [Array<String>] Command used to execute commands.
-  def self.command_executer=(val)
-    @@command_executer = val
   end
 end