code: func (e *encoder) nextSpecialChar(p []byte) (i int) {
  	for i = 0; i < len(p); i++ {
  		// ASCII 32-126 (printable) + '\t' - '=' can appear in the qprintable stream
  		if !((p[i] >= 32 && p[i] <= 126 && p[i] != byte('=')) || p[i] == byte('\t')) {
  			return i
  		}
  	}
  	return i
  }
docs: // Return first character position where the character has to be escaped