class_docstr: A reward scheme that rewards the agent for increasing its net worth,
  while penalizing more volatile strategies.
  
  Parameters
  ----------
  return_algorithm : {'sharpe', 'sortino'}, Default 'sharpe'.
      The risk-adjusted return metric to use.
  risk_free_rate : float, Default 0.
      The risk free rate of returns to use for calculating metrics.
  target_returns : float, Default 0
      The target returns per period for use in calculating the sortino ratio.
  window_size : int
      The size of the look back window for computing the reward.
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docstr: Computes the sharpe ratio for a given series of a returns.
  
  Parameters
  ----------
  returns : `pd.Series`
      The returns for the `portfolio`.
  
  Returns
  -------
  float
      The sharpe ratio for the given series of a `returns`.
  
  References
  ----------
  .. [1] https://en.wikipedia.org/wiki/Sharpe_ratio
docstr_tok: ["Computes","the","sharpe","ratio","for","a","given","series","of","a","returns",".","Parameters","--","--","--","--","--","returns",":","`","pd.Series","`","The","returns","for","the","`","portfolio","`",".","Returns","--","--","--","-","float","The","sharpe","ratio","for","the","given","series","of","a","`","returns","`",".","References","--","--","--","--","--","..","[","1","]","https",":","\/\/en.wikipedia.org\/wiki\/Sharpe_ratio"]
code: def _sharpe_ratio(self, returns: "pd.Series") -> float:
      """Computes the sharpe ratio for a given series of a returns.
  
      Parameters
      ----------
      returns : `pd.Series`
          The returns for the `portfolio`.
  
      Returns
      -------
      float
          The sharpe ratio for the given series of a `returns`.
  
      References
      ----------
      .. [1] https://en.wikipedia.org/wiki/Sharpe_ratio
      """
      return (np.mean(returns) - self._risk_free_rate + 1e-9) / (
          np.std(returns) + 1e-9
      )
  
imports: from abc import abstractmethod
  import numpy
  import pandas
  from tensortrade.env.generic import RewardScheme, TradingEnv
  from tensortrade.feed.core import Stream, DataFeed
  import math
label_desc: Use image node_id 2 for calling the RiskAdjustedReturns obj's underlying member method code with example usage: obj._sharpe_ratio(returns) and returns: unknown