code: func (t *Terminal) countToLeftWord() int {
  	if t.pos == 0 {
  		return 0
  	}
  
  	pos := t.pos - 1
  	for pos > 0 {
  		if t.line[pos] != ' ' {
  			break
  		}
  		pos--
  	}
  	for pos > 0 {
  		if t.line[pos] == ' ' {
  			pos++
  			break
  		}
  		pos--
  	}
  
  	return t.pos - pos
  }
docs: // countToLeftWord returns then number of characters from the cursor to the
  // start of the previous word.