Function append

append(
    user: Identity,
    crypto: Implementation,
    opts: {
        content: Content;
        getBySeq: (seq: number) => Promise<SignedPost>;
        prev: SignedPost;
    },
): Promise<SignedPost>
Create a new message following the given previous message.
Parameters
- user: Identity
- crypto: Implementation
- opts: {
      content: Content;
      getBySeq: (seq: number) => Promise<SignedPost>;
      prev: SignedPost;
  }
Returns Promise<SignedPost>
- Defined in index.ts:194