Macro migration 

macro_rules! migration {
    (
        $db:ty, $op:ty, $app_name:literal, $migration_name:literal, $parents:expr, $operations:expr
    ) => { ... };
}

Macro for implementing the Migration trait for the provided database.

This macro will use current file name as name for migration

This macro expects the following arguments:

• $db:ty: the type of database
• $op:ty: The type for which the migration is being implemented
• $app_name:literal: Name of app to be used for app variable
• $migration_name:literal: Name of migration to be used for the name function
• $parents:expr: List of parents migration.
• $operations:expr: List of operations