capybara/virtualenv/lib/python2.7/site-packages/pip/_vendor/html5lib/treewalkers/_base.py
def to_text(s, blank_if_none=True):
    """Wrapper around six.text_type to convert None to empty string"""
    if s is None:
        if blank_if_none:
            return ""
        else:
            return None
    elif isinstance(s, text_type):
        return s
    else:
        return text_type(s)
def to_text(s, blank_if_none=True):
    """Wrapper around six.text_type to convert None to empty string"""
    if s is None:
        if blank_if_none:
            return ""
        else:
            return None
    elif isinstance(s, text_type):
        return s
    else:
        return text_type(s)
Wrapper around six.text_type to convert None to empty string