def prompt_for_password(prompt=None, no_colon=False, stream=None):
    """
    Prompts for and returns a new password if required; otherwise, returns
    None.
    A trailing colon is appended unless ``no_colon`` is True.
    If the user supplies an empty password, the user will be re-prompted until
    they enter a non-empty password.
    ``prompt_for_password`` autogenerates the user prompt based on the current
    host being connected to. To override this, specify a string value for
    ``prompt``.
    ``stream`` is the stream the prompt will be printed to; if not given,
    defaults to ``sys.stderr``.
    """
Get a password from the user in Fabric, not echoing the value