def remove filename
      return false unless source_hash.key?(filename)
      source_hash.delete filename
      true
    end
def remove filename
      return false unless source_hash.key?(filename)
      source_hash.delete filename
      true
    end
Remove a source from the workspace. The source will not be removed if
 its file exists and the workspace is configured to include it.

 @param filename [String]
 @return [Boolean] True if the source was removed from the workspace