text: """Portfolio ratios"""
  
  from typing import Union
  
  import pandas as pd
  
  
  def get_sharpe_ratio(
      pf_return: Union[float, pd.Series],
      rf_return: float,
      std_deviation: Union[float, pd.Series],
  ) -> Union[float, pd.Series]:
      """
      Calculate Sharpe ratio.
      """
      return (pf_return - rf_return) / std_deviation
  