def understand?(name, arity = nil)
      name = name.to_s
      !!find { |m| m.name == name && (!arity || m.arity == arity) }
    end
def understand?(name, arity = nil)
      name = name.to_s
      !!find { |m| m.name == name && (!arity || m.arity == arity) }
    end
Returns true if it is required to understand the