parameters: (expr)
docstring: Make sure an expression is not an empty string
  
      Parameters
      ----------
      expr : object
          An object that can be converted to a string
  
      Raises
      ------
      ValueError
        * If expr is an empty string
docstring_summary: Make sure an expression is not an empty string
docstring_tokens: Make sure an expression is not an empty string
function: def _check_expression(expr):
      """Make sure an expression is not an empty string
  
      Parameters
      ----------
      expr : object
          An object that can be converted to a string
  
      Raises
      ------
      ValueError
        * If expr is an empty string
      """
      if not expr:
          raise ValueError("expr cannot be an empty string")
function_tokens: def _check_expression ( expr ) : if not expr : raise ValueError ( "expr cannot be an empty string" )