code: func (c *Corpus) WordProb(word string) (float64, bool) {
  	id, ok := c.Id(word)
  	if !ok {
  		return 0, false
  	}
  
  	count := c.frequencies[id]
  	return float64(count) / float64(c.totalFreq), true
  
  }
docs: // WordProb returns the probability of a word appearing in the corpus.