text: import sys
  import textwrap
  
  from pip._internal.cli.base_command import Command
  from pip._internal.cli.status_codes import SUCCESS
  from pip._internal.utils.misc import get_prog
  from pip._internal.utils.typing import MYPY_CHECK_RUNNING
  
  if MYPY_CHECK_RUNNING:
      from optparse import Values
      from typing import List
  
  BASE_COMPLETION = """
  # pip {shell} completion start{script}# pip {shell} completion end
  """
  
  COMPLETION_SCRIPTS = {
      'bash': """
          _pip_completion()
          {{
              COMPREPLY=( $( COMP_WORDS="${{COMP_WORDS[*]}}" \\
                             COMP_CWORD=$COMP_CWORD \\
                             PIP_AUTO_COMPLETE=1 $1 2>/dev/null ) )
          }}
          complete -o default -F _pip_completion {prog}
      """,
      'zsh': """
          function _pip_completion {{
            local words cword
            read -Ac words
            read -cn cword
            reply=( $( COMP_WORDS="$words[*]" \\
                       COMP_CWORD=$(( cword-1 )) \\
                       PIP_AUTO_COMPLETE=1 $words[1] 2>/dev/null ))
          }}
          compctl -K _pip_completion {prog}
      """,
      'fish': """
          function __fish_complete_pip
              set -lx COMP_WORDS (commandline -o) ""
              set -lx COMP_CWORD ( \\
                  math (contains -i -- (commandline -t) $COMP_WORDS)-1 \\
              )
              set -lx PIP_AUTO_COMPLETE 1
              string split \\  -- (eval $COMP_WORDS[1])
          end
          complete -fa "(__fish_complete_pip)" -c {prog}
      """,
  }
  
  
  class CompletionCommand(Command):
      """A helper command to be used for command completion."""
  
      ignore_require_venv = True
  
      def add_options(self):
          # type: () -> None
          self.cmd_opts.add_option(
              '--bash', '-b',
              action='store_const',
              const='bash',
              dest='shell',
              help='Emit completion code for bash')
          self.cmd_opts.add_option(
              '--zsh', '-z',
              action='store_const',
              const='zsh',
              dest='shell',
              help='Emit completion code for zsh')
          self.cmd_opts.add_option(
              '--fish', '-f',
              action='store_const',
              const='fish',
              dest='shell',
              help='Emit completion code for fish')
  
          self.parser.insert_option_group(0, self.cmd_opts)
  
      def run(self, options, args):
          #  type: (Values, List[str]) -> int
          """Prints the completion code of the given shell"""
          shells = COMPLETION_SCRIPTS.keys()
          shell_options = ['--' + shell for shell in sorted(shells)]
          if options.shell in shells:
              script = textwrap.dedent(
                  COMPLETION_SCRIPTS.get(options.shell, '').format(
                      prog=get_prog())
              )
              print(BASE_COMPLETION.format(script=script, shell=options.shell))
              return SUCCESS
          else:
              sys.stderr.write(
                  'ERROR: You must pass {}\n' .format(' or '.join(shell_options))
              )
              return SUCCESS
  