import ast


def exp_parse(expression):
    """Convert an expression string into an ast object

    Args:
        expression (str): expression string

    Returns:
        ast.AST: ast tree from the expression, starting from ast.Expression node

    """
    # mode='exec' (default) for sequence of statements
    # eval - single expression
    # single - single interactive statement
    return ast.parse(expression, "<string>", mode="eval")