code: func (c *Client) AddEnvVar(account, repo, name, value string) (*EnvVar, error) {
  	envVar := &EnvVar{}
  
  	err := c.request("POST", fmt.Sprintf("project/%s/%s/envvar", account, repo), envVar, nil, &EnvVar{Name: name, Value: value})
  	if err != nil {
  		return nil, err
  	}
  
  	return envVar, nil
  }
docs: // AddEnvVar adds a new environment variable to the specified project
  // Returns the added env var (the value will be masked)