def image(size = '300x300', is_gray = false, category = nil, number = nil, text = nil)
raise ArgumentError, 'Size should be specified in format 300x300' unless size.match(/^[0-9]+x[0-9]+$/)
raise ArgumentError, "Supported categories are #{SUPPORTED_CATEGORIES.join(', ')}" unless category.nil? || SUPPORTED_CATEGORIES.include?(category)
raise ArgumentError, 'Category required when number is passed' if !number.nil? && category.nil?
raise ArgumentError, 'Number must be between 1 and 10' unless number.nil? || (1..10).include?(number)
raise ArgumentError, 'Category and number must be passed when text is passed' if !text.nil? && number.nil? && category.nil?
url_parts = ['http://lorempixel.com']
url_parts << 'g' if is_gray
url_parts += size.split('x')
url_parts += [category, number, text].compact
url_parts.join('/')
end