IndentationError from comment in python

Why does python react to comment indents?

def foo():
    """
    Random comment
    """
    return True

works, but:

def foo():
"""
Random comment
"""
    return True

not working throwing an IndentationError.

It seems strange to me, since comments should not be more than comments. And by the way, this works:

def foo():
# Another random comment
    return True