code: def ffill(groupby, limit=None):
      """
      Forward fill the values.
  
      limit:  int, default None
              Limit number of values to fill
  
      return: Series or DataFrame
      """
      op = GroupByFFill(limit=limit)
      return op(groupby)
  
imports: import numpy
  import pandas
  from ...None import opcodes
  from ...core import OutputType
  from ...serialization.serializables import AnyField, DictField, StringField, Int64Field
  from ..utils import parse_index, build_empty_df, build_empty_series
  from ..operands import DataFrameOperandMixin, DataFrameOperand
label_desc: Use image node_id 1 for calling a global function with example usage: ffill(groupby, limit) and returns: op