<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def ensure_source_package_dir(nb_path, pkg_name):
 """Ensure all of the important directories in a source package exist"""


    pkg_path = join(dirname(nb_path), pkg_name)

    makedirs(join(pkg_path,'notebooks'),exist_ok=True)
    makedirs(join(pkg_path, 'docs'), exist_ok=True)

    return pkg_path