def modified_lines_in_file(file)
      subcmd = 'show --format=%n'
      @modified_lines ||= {}
      @modified_lines[file] ||=
        Overcommit::GitRepo.extract_modified_lines(file, subcmd: subcmd)
    end
def modified_lines_in_file(file)
      subcmd = 'show --format=%n'
      @modified_lines ||= {}
      @modified_lines[file] ||=
        Overcommit::GitRepo.extract_modified_lines(file, subcmd: subcmd)
    end
Returns the set of line numbers corresponding to the lines that were
 changed in a specified file.