interface Searchable {
  search(query: String, filter: String): SearchResult
  fetch(id: ID!): FetchResult
}

type SearchResult {
  id: ID!
}

type FetchResult {
  id: ID!
}

type Book implements Searchable {
  # Implements the search field from Searchable and adds an additional, optional argument. This is ok.
  search(query: String, filter: String, genre: String): SearchResult
  
  # Error: Implements the fetch field from Searchable, but with a different type.
  fetch(id: String!): FetchResult
}

# Implement the interface with a type that adds a required argument - invalid
type Video implements Searchable {
  # Implements the search field from Searchable, which is valid
  search(query: String, filter: String): SearchResult
  
  # Attempts to implement the fetch field but adds a required 'region' argument
  # This is invalid as it adds a required argument which the interface does not specify
  fetch(id: ID!, region: String!): FetchResult
}

# Implement the interface with a type that is missing an argument from the interface. Invalid.
type Coffee implements Searchable {
  # Missing `filter`
  search(query: String): SearchResult
  fetch(id: ID!): FetchResult
}