def modified_lines_in_file(file)
      @modified_lines ||= {}
      unless @modified_lines[file]
        @modified_lines[file] =
          Overcommit::GitRepo.extract_modified_lines(file, staged: true)

        # Include lines modified in last commit if amending
        if amendment?
          subcmd = 'show --format=%n'
          @modified_lines[file] +=
            Overcommit::GitRepo.extract_modified_lines(file, subcmd: subcmd)
        end
      end
      @modified_lines[file]
    end
def modified_lines_in_file(file)
      @modified_lines ||= {}
      unless @modified_lines[file]
        @modified_lines[file] =
          Overcommit::GitRepo.extract_modified_lines(file, staged: true)

        # Include lines modified in last commit if amending
        if amendment?
          subcmd = 'show --format=%n'
          @modified_lines[file] +=
            Overcommit::GitRepo.extract_modified_lines(file, subcmd: subcmd)
        end
      end
      @modified_lines[file]
    end
Returns the set of line numbers corresponding to the lines that were
 changed in a specified file.