merge does not understand "extend" word

[eugeneK1968]

Hello.
I have few schema files loading by server:
------- 1.graphql ---------------
type Query {
}
------ 2.graphql ---------------
type User {
id: ID!
}
extend type Query {
getUser(userId: ID!) : User
}
------ 3.graphql ---------------
type Category {
id: ID!
}
extend type Query {
getCategory(userId: ID!, categoryId: ID!) : Category
}

The problem is that "gql" tool "merge" option does not understand word "extend" that is a legal
word for graphql schema syntax.