class_docstr: Based on ffn's GroupStats with a few extra helper methods.
  
  Args:
      * backtests (list): List of backtests
  
  Attributes:
      * backtest_list (list): List of bactests in the same order as provided
      * backtests (dict): Dict of backtests by name
class_docstr_tok: ["Based","on","ffn","'s","GroupStats","with","a","few","extra","helper","methods",".","Args",":","*","backtests","(","list",")",":","List","of","backtests","Attributes",":","*","backtest_list","(","list",")",":","List","of","bactests","in","the","same","order","as","provided","*","backtests","(","dict",")",":","Dict","of","backtests","by","name"]
docstr: Plots the return histogram of a given backtest over time.
  
  Args:
      * backtest (str, int): Backtest. Can be either a index (int) or the
          name (str)
      * kwds (dict): Keywords passed to plot_histogram
docstr_tok: ["Plots","the","return","histogram","of","a","given","backtest","over","time",".","Args",":","*","backtest","(","str",",","int",")",":","Backtest",".","Can","be","either","a","index","(","int",")","or","the","name","(","str",")","*","kwds","(","dict",")",":","Keywords","passed","to","plot_histogram"]
code: def plot_histogram(self, backtest=0, **kwds):
      """
      Plots the return histogram of a given backtest over time.
  
      Args:
          * backtest (str, int): Backtest. Can be either a index (int) or the
              name (str)
          * kwds (dict): Keywords passed to plot_histogram
  
      """
      key = self._get_backtest(backtest)
      self[key].plot_histogram(**kwds)
  
imports: from __future__ import division
  from copy import deepcopy
  import bt
  import ffn
  import pandas
  import numpy
  from matplotlib import pyplot
  import pyprind
  from tqdm import tqdm
label_desc: Use image node_id 7 for calling the Result obj's underlying member method code with example usage: obj.plot_histogram(backtest) without return types