def binop_return_dtype(op, left, right):
 if is_comparison(op):
  if (left != right):
   raise TypeError("Don't know how to compute {left} {op} {right}.\nComparisons are only supported between Factors of equal dtypes.".format(left=left, op=op, right=right))
  return bool_dtype
 elif ((left != float64_dtype) or (right != float64_dtype)):
  raise TypeError("Don't know how to compute {left} {op} {right}.\nArithmetic operators are only supported between Factors of dtype 'float64'.".format(left=left.name, op=op, right=right.name))
 return float64_dtype

def binop_return_dtype ( op , left , right ) : if is_comparison ( op ) : if ( left != right ) : raise TypeError ( "Don't know how to compute {left} {op} {right}.\nComparisons are only supported between Factors of equal dtypes." . format ( left = left , op = op , right = right ) ) return bool_dtype elif ( ( left != float64_dtype ) or ( right != float64_dtype ) ) : raise TypeError ( "Don't know how to compute {left} {op} {right}.\nArithmetic operators are only supported between Factors of dtype 'float64'." . format ( left = left . name , op = op , right = right . name ) ) return float64_dtype
compute the expected return dtype for the given binary operator .