<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def send_verification_mail(request, user, verification_type):
 """ Sends an email with a verification link to users when ``ACCOUNTS_VERIFICATION_REQUIRED`` is ```True`` and they're signing up, or when they reset a lost password. The ``verification_type`` arg is both the name of the urlpattern for the verification link, as well as the names of the email templates to use. """

    verify_url = reverse(verification_type, kwargs={
        "uidb36": int_to_base36(user.id),
        "token": default_token_generator.make_token(user),
    }) + "?next=" + (next_url(request) or "/")
    context = {
        "request": request,
        "user": user,
        "verify_url": verify_url,
    }
    subject_template_name = "email/%s_subject.txt" % verification_type
    subject = subject_template(subject_template_name, context)
    send_mail_template(subject, "email/%s" % verification_type,
                       settings.DEFAULT_FROM_EMAIL, user.email,
                       context=context)