code: def _align(terms):
      
      try:
          # flatten the parse tree (a nested list, really)
          terms = list(com.flatten(terms))
      except TypeError:
          # can't iterate so it must just be a constant or single variable
          if isinstance(terms.value, pd.core.generic.NDFrame):
              typ = type(terms.value)
              return typ, _zip_axes_from_type(typ, terms.value.axes)
          return np.result_type(terms.type), None
  
      # if all resolved variables are numeric scalars
      if all(term.is_scalar for term in terms):
          return _result_type_many(*(term.value for term in terms)).type, None
  
      # perform the main alignment
      typ, axes = _align_core(terms)
      return typ, axes
docs: Align a set of terms