code: def _replace_interval_with_scalar(expr):
      
      try:
          expr_op = expr.op()
      except AttributeError:
          expr_op = None
  
      if not isinstance(expr, (dt.Interval, ir.IntervalValue)):
          # Literal expressions have op method but native types do not.
          if isinstance(expr_op, ops.Literal):
              return expr_op.value
          else:
              return expr
      elif isinstance(expr, dt.Interval):
          try:
              microseconds = _map_interval_to_microseconds[expr.unit]
              return microseconds
          except KeyError:
              raise ValueError(
                  "Expected preceding values of week(), "
                  + "day(), hour(), minute(), second(), millisecond(), "
                  + "microseconds(), nanoseconds(); got {}".format(expr)
              )
      elif expr_op.args and isinstance(expr, ir.IntervalValue):
          if len(expr_op.args) > 2:
              raise com.NotImplementedError(
                  "'preceding' argument cannot be parsed."
              )
          left_arg = _replace_interval_with_scalar(expr_op.args[0])
          right_arg = _replace_interval_with_scalar(expr_op.args[1])
          method = _map_interval_op_to_op[type(expr_op)]
          return method(left_arg, right_arg)
docs: Good old Depth-First Search to identify the Interval and IntervalValue
      components of the expression and return a comparable scalar expression.
  
      Parameters
      ----------
      expr : float or expression of intervals
          For example, ``ibis.interval(days=1) + ibis.interval(hours=5)``
  
      Returns
      -------
      preceding : float or ir.FloatingScalar, depending upon the expr