code: def add_features(frame, fdict, flen, prefix=""):
      r"""Add new features to a dataframe with the specified dictionary.
  
      Parameters
      ----------
      frame : pandas.DataFrame
          The dataframe to extend with new features defined by ``fdict``.
      fdict : dict
          A dictionary of column names (key) and data types (value).
      flen : int
          Length of ``frame``.
      prefix : str, optional
          Prepend all columns with a prefix.
  
      Returns
      -------
      frame : pandas.DataFrame
          The dataframe with the added features.
  
      """
      # generate sequences
      seqint = [0] * flen
      seqfloat = [0.0] * flen
      seqbool = [False] * flen
      # initialize new fields in frame
      for key, value in list(fdict.items()):
          newkey = key
          if prefix:
              newkey = PSEP.join([prefix, newkey])
          if value == int:
              frame[newkey] = pd.Series(seqint)
          elif value == float:
              frame[newkey] = pd.Series(seqfloat)
          elif value == bool:
              frame[newkey] = pd.Series(seqbool)
          else:
              raise ValueError(
                  "Type to generate feature series not found"
              )
      return frame
  
imports: import warnings
  from alphapy.__main__ import main_pipeline
  from alphapy.frame import read_frame
  from alphapy.frame import write_frame
  from alphapy.globals import ModelType
  from alphapy.globals import Partition, datasets
  from alphapy.globals import PSEP, SSEP, USEP
  from alphapy.globals import WILDCARD
  from alphapy.model import get_model_config
  from alphapy.model import Model
  from alphapy.space import Space
  from alphapy.utilities import valid_date
  import argparse
  import datetime
  from itertools import groupby
  import logging
  import math
  import numpy
  import os
  import pandas
  import sys
  import yaml
label_desc: Use image node_id 9 for calling a global function with example usage: add_features(frame, fdict, flen, prefix) and returns: frame