class_docstr: Object serving as a base class for all engines.
class_docstr_tok: ["Object","serving","as","a","base","class","for","all","engines","."]
code: def __init__(self, expr):
      self.expr = expr
      self.aligned_axes = None
      self.result_type = None
  
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 1 to create a new AbstractEngine object from inherited base classes: object with example: obj = AbstractEngine(expr)