capybara/virtualenv/lib/python2.7/site-packages/setuptools/dist.py
def check_extras(dist, attr, value):
    """Verify that extras_require mapping is valid"""
    try:
        for k,v in value.items():
            if ':' in k:
                k,m = k.split(':',1)
                if pkg_resources.invalid_marker(m):
                    raise DistutilsSetupError("Invalid environment marker: "+m)
            list(pkg_resources.parse_requirements(v))
    except (TypeError,ValueError,AttributeError):
        raise DistutilsSetupError(
            "'extras_require' must be a dictionary whose values are "
            "strings or lists of strings containing valid project/version "
            "requirement specifiers."
        )
def check_extras(dist, attr, value):
    """Verify that extras_require mapping is valid"""
    try:
        for k,v in value.items():
            if ':' in k:
                k,m = k.split(':',1)
                if pkg_resources.invalid_marker(m):
                    raise DistutilsSetupError("Invalid environment marker: "+m)
            list(pkg_resources.parse_requirements(v))
    except (TypeError,ValueError,AttributeError):
        raise DistutilsSetupError(
            "'extras_require' must be a dictionary whose values are "
            "strings or lists of strings containing valid project/version "
            "requirement specifiers."
        )
def check_extras ( dist , attr , value ) : try : for k , v in value . items ( ) : if ':' in k : k , m = k . split ( ':' , 1 ) if pkg_resources . invalid_marker ( m ) : raise DistutilsSetupError ( "Invalid environment marker: " + m ) list ( pkg_resources . parse_requirements ( v ) ) except ( TypeError , ValueError , AttributeError ) : raise DistutilsSetupError ( "'extras_require' must be a dictionary whose values are " "strings or lists of strings containing valid project/version " "requirement specifiers." )
Verify that extras_require mapping is valid
Verify that extras_require mapping is valid