docstr: Evaluate a marker.
  
  Return the boolean from evaluating the given marker against the
  environment. environment is an optional argument to override all or
  part of the determined environment.
  
  The environment is determined from the current Python process.
docstr_tok: ["Evaluate","a","marker",".","Return","the","boolean","from","evaluating","the","given","marker","against","the","environment",".","environment","is","an","optional","argument","to","override","all","or","part","of","the","determined","environment",".","The","environment","is","determined","from","the","current","Python","process","."]
code: def evaluate(
      self, environment: Optional[Dict[str, str]] = None
  ) -> bool:
      """Evaluate a marker.
  
      Return the boolean from evaluating the given marker against the
      environment. environment is an optional argument to override all or
      part of the determined environment.
  
      The environment is determined from the current Python process.
      """
      current_environment = default_environment()
      if environment is not None:
          current_environment.update(environment)
  
      return _evaluate_markers(self._markers, current_environment)
  
imports: import operator
  import os
  import platform
  import sys
  from typing import Any, Callable, Dict, List, Optional, Tuple, Union
  from pyparsing import Forward, Group, Literal, ParseException, ParseResults, QuotedString, ZeroOrMore, stringEnd, stringStart
  from .specifiers import InvalidSpecifier, Specifier
label_desc: Use image node_id 4 for calling the Marker obj's underlying member method code with example usage: obj.evaluate(environment) and returns: _evaluate_markers