def deepest_path(path_a, path_b):
 if (path_a == '.'):
  path_a = ''
 if (path_b == '.'):
  path_b = ''
 if path_a.startswith(path_b):
  return (path_a or '.')
 if path_b.startswith(path_a):
  return (path_b or '.')
 return None

def deepest_path ( path_a , path_b ) : if ( path_a == '.' ) : path_a = '' if ( path_b == '.' ) : path_b = '' if path_a . startswith ( path_b ) : return ( path_a or '.' ) if path_b . startswith ( path_a ) : return ( path_b or '.' ) return None
return the deepest of two paths .