class_docstr: Object serving as a base class for all engines.
class_docstr_tok: ["Object","serving","as","a","base","class","for","all","engines","."]
docstr: Return an evaluated expression.
  
  Parameters
  ----------
  env : Scope
      The local and global environment in which to evaluate an
      expression.
  
  Notes
  -----
  Must be implemented by subclasses.
docstr_tok: ["Return","an","evaluated","expression",".","Parameters","--","--","--","--","--","env",":","Scope","The","local","and","global","environment","in","which","to","evaluate","an","expression",".","Notes","--","--","-","Must","be","implemented","by","subclasses","."]
code: def _evaluate(self):
      """Return an evaluated expression.
  
      Parameters
      ----------
      env : Scope
          The local and global environment in which to evaluate an
          expression.
  
      Notes
      -----
      Must be implemented by subclasses.
      """
      pass
  
imports: import abc
  from pandas.compat import map
  from pandas import compat
  from pandas.core.computation.align import _align, _reconstruct_object
  from pandas.core.computation.ops import UndefinedVariableError, _mathops, _reductions
  import pandas.io.formats.printing
label_desc: Use image node_id 5 for calling the AbstractEngine obj's underlying member method code with example usage: obj._evaluate() without return types