Bug Description
The enum generator fails to properly handle binary expressions like 'iota + 1' in enum declarations.
Example:
When defining an enum with iota + 1, the first constant is missing from the generated code.
Root Cause:
The parser in generator.go only handles plain iota identifiers but doesn't handle binary expressions like iota + 1, which are common in enum declarations.
Fix Needed:
Add support for ast.BinaryExpr to handle expressions like iota + 1, iota + 2, etc.