def flag?(flag)
      key = canonical_key(flag)
      state = flags[key] if flags?
      state = environment_flag?(key) if state.nil?

      case state
      when nil then nil
      else state.to_s == 'true'
      end
    end
def flag?(flag)
      key = canonical_key(flag)
      state = flags[key] if flags?
      state = environment_flag?(key) if state.nil?

      case state
      when nil then nil
      else state.to_s == 'true'
      end
    end
Returns the boolean state of the flag as found in options[:answers],
 or if not found in the answers, then it checks for an environment variable.

 @param String flag key
 @return [Boolean,nil] boolean true or false unless not found at all, then nil.