parameters: (self, names, helptext, validator=None, impl=None)
docstring: Initializes Command from names and helptext, plus optional callables.
  
      Args:
        names:       command name, or list of synonyms
        helptext:    brief string description of the command
        validator:   callable for custom argument validation
                     Should raise ParseError if it wants
        impl:        callable to be invoked when command is called
docstring_summary: Initializes Command from names and helptext, plus optional callables.
docstring_tokens: Initializes Command from names and helptext plus optional callables .
function: def __init__(self, names, helptext, validator=None, impl=None):
      """Initializes Command from names and helptext, plus optional callables.
  
      Args:
        names:       command name, or list of synonyms
        helptext:    brief string description of the command
        validator:   callable for custom argument validation
                     Should raise ParseError if it wants
        impl:        callable to be invoked when command is called
      """
      self.names = names
      self.validator = validator
      self.helptext = helptext
      self.impl = impl
      self.args = []
      self.required_groups = []
      self.arg_dict = {}
      self.positional_args = []
      self.cmdline = None
function_tokens: def __init__ ( self , names , helptext , validator = None , impl = None ) : self . names = names self . validator = validator self . helptext = helptext self . impl = impl self . args = [ ] self . required_groups = [ ] self . arg_dict = { } self . positional_args = [ ] self . cmdline = None