class Addressable::Template

def normalize_keys(mapping)
  return mapping.inject({}) do |accu, pair|
    name, value = pair
    if Symbol === name
      name = name.to_s
    elsif name.respond_to?(:to_str)
      name = name.to_str
    else
      raise TypeError,
        "Can't convert #{name.class} into String."
    end
    accu[name] = value
    accu
  end
end