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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def obj_to_string(obj):
    '''Render an object into a unicode string if possible'''
    if not obj:
        return None
    elif isinstance(obj, bytes):
        return obj.decode('utf-8')
    elif isinstance(obj, basestring):
        return obj
    elif is_lazy_string(obj):
        return obj.value
    elif hasattr(obj, '__html__'):
        return obj.__html__()
    else:
        return str(obj)