try:
    STRING_TYPES = (str, unicode)
except NameError:           #pragma NO COVER Python >= 3.0
    STRING_TYPES = (str,)

try:
    u = unicode
except NameError:           #pragma NO COVER Python >= 3.0
    u = str
    b = bytes
else:                       #pragma NO COVER Python < 3.0
    b = str

try:
    from StringIO import StringIO
except ImportError:         #pragma NO COVER Python >= 3.0
    from io import StringIO
    from io import BytesIO
else:                       #pragma NO COVER Python < 3.0
    BytesIO = StringIO


def must_decode(value):     #pragma NO COVER
    if type(value) is bytes:
        try:
            return value.decode('utf-8')
        except UnicodeDecodeError:
            return value.decode('latin1')
    return value

def must_encode(value):     #pragma NO COVER
    if type(value) is u:
        return value.encode('utf-8')
    return value