isIdentity = (identity) => {
  return Boolean(identity.id &&
    identity.hash &&
    identity.bytes &&
    identity.publicKey &&
    identity.signatures &&
    identity.signatures.id &&
    identity.signatures.publicKey &&
    identity.type)
}
Verifies whether an identity is valid.
@param {Identity} identity The identity to verify.
@return {boolean} True if the identity is valid, false otherwise.
@static
@private