I get error "undefined method 'add_column'" when trying to perform what appears to be a valid migration

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When attempting to migrate

```crystal
class CreateListAndListEntry::V20180930082950 < LuckyRecord::Migrator::Migration::V1
def migrate
create :list_entries do
add title : String
add_belongs_to list : List, on_delete: :do_nothing
add_belongs_to author : User, on_delete: :cascade
end
create :lists do
add title : String
end
alter :users do
add list_entries : ListEntry, fill_existing_with: :nothing
end
end

def rollback
drop :list_entries
drop :lists
alter :users do
remove :list_entries
end
end
end
```

I receive the following error message: [undefined method 'add_column'](https://github.com/dscottboggs/lucky-shopping-list/blob/master/ERROR.txt)

You can find the whole project here https://github.com/dscottboggs/lucky-shopping-list

thanks for the help

Start with the migration shown in the issue and the linked ERROR.txt, then reproduce the failure in the lucky-shopping-list project. Trace the migration operation that reports undefined method 'add_column' and compare it with the supported Avram migration API. Done means the migration runs without that error or the issue documents the required migration syntax.

Written by the indexing model from the issue text.