def normalise_email(email):
 clean_email = email.strip()
 if ('@' in clean_email):
  (local, host) = clean_email.split('@')
  return ((local + '@') + host.lower())
 return clean_email

def normalise_email ( email ) : clean_email = email . strip ( ) if ( '@' in clean_email ) : ( local , host ) = clean_email . split ( '@' ) return ( ( local + '@' ) + host . lower ( ) ) return clean_email
the local part of an email address is case-sensitive .