import numpy as numpy

this means explicit re-export, as mentioned in PEP484:

Modules and variables imported into the stub are not considered exported from the stub unless the import uses the import ... as ... form or the equivalent from ... import ... as ... form. (UPDATE: To clarify, the intention here is that only names imported using the form X as X will be exported, i.e. the name before and after as must be the same.)

perhaps this rule should be removed, since it contradicts type checking rules