import os

def project_home():
    path = os.environ.get('PYTHONPATH')
    if not path:
        raise Exception('No environment variables of PYTHONPATH.')
    here = os.path.dirname(__file__).replace("\\", '/')
    for j in [i.replace("\\", '/').strip() for i in path.split(os.pathsep)]:
        if here.startswith(j):
            return j
    else:
        raise Exception('Project directory is not in PYTHONPATH.')