code: func (e *EnvVar) Set(key, value string) {
  	keyVal := key + "=" + value
  	for i, v := range *e {
  		env := strings.SplitN(v, "=", 2)
  		if len(env) < 2 {
  			continue
  		}
  		if env[0] == key {
  			(*e)[i] = keyVal
  			return
  		}
  	}
  	*e = append(*e, keyVal)
  }
docs: // Set sets the environment key to value.