code: def replace(self, col: str, searchval: str, replaceval: str):
          
          try:
              self.df[col] = self.df[col].replace(searchval, replaceval)
          except Exception as e:
              self.err(e, "Can not replace value in column")
docs: Replace a value in a column in the main dataframe
  
          :param col: column name
          :type col: str
          :param searchval: value to replace
          :type searchval: str
          :param replaceval: new value
          :type replaceval: str
  
          :example: ``ds.replace("mycol", "value", "new_value")``