I have seen this issue : #10
but the solution suggested my @13muskanp does not work for me as after changing from

from aster.protos import pipeline_pb2
from aster.builders import model_builder
to this:
from protos import pipeline_pb2
from builders import model_builder

It is still throwing an error that no module aster is found in the other files of the different directories like builders, covnets, protos etc