def listNamespaces(root=None, recursive=False, internal=False):
    return Namespace(root or ":").listNamespaces(recursive, internal)
Returns a list of the namespaces in the scene
dataset/ETHPy150Open CountZer0/PipelineConstructionSet/python/maya/site-packages/pymel-1.0.3/pymel/core/system.py/listNamespaces