class Pry::Method

def signature
  if respond_to?(:parameters)
    args = parameters.inject([]) do |args_array, (arg_type, name)|
      name ||= (arg_type == :block ? 'block' : "arg#{args_array.size + 1}")
      args_array.push(
        case arg_type
        when :req    then name.to_s
        when :opt    then "#{name}=?"
        when :rest   then "*#{name}"
        when :block  then "&#{name}"
        when :key    then "#{name}:?"
        when :keyreq then "#{name}:"
        else '?'
        end
      )
    end
  else
    args = (1..arity.abs).map { |i| "arg#{i}" }
    args[-1] = "*#{args[-1]}" if arity < 0
  end
  "#{name}(#{args.join(', ')})"
end