input: Write a function to filter alphanumeric strings.
  assert filter_alphanumeric(['hello', 'world', '1234', '56jklm']) == ['hello', 'world', '1234', '56jklm']
  assert filter_alphanumeric(['!@#$', '%^&*', 'abc123', 'xyz!']) == ['abc123']
  assert filter_alphanumeric(['', '   ', 'test1', '2cool']) == ['test1', '2cool']
output: def filter_alphanumeric(strings):
      return [s for s in strings if s.isalnum() or (any(c.isalnum() for c in s) and all(c.isalnum() or c.isspace() for c in s))]