docs: def set_attr_text(self, attr_key, attr_val, el_idx=0):
          """Set the value of the selected attribute of the selected element.
  
          Args:
            attr_key : str
              Name of attribute for which to search
  
            attr_val : str
              Text to set for the attribute.
  
            el_idx : int
              Index of element to use in the event that there are multiple sibling
              elements with the same name.
  
          """
          self.get_element_by_attr_key(attr_key, el_idx).attrib[attr_key] = attr_val