* add core types and type checking function
* fix unit test bug
* avoid defining dynamic classes
* typo fix
* add component metadata format
* add a construct for the component decorator
* add default values for the meta classes
* add input/output types to the metadata
* add from_dict in TypeMeta
* small fix
* add unit tests
* use python struct for the openapi schema
* add default in parameter
* add default value
* remove the str restriction for the param default
* bug fix
* add pipelinemeta
* add pipeline metadata
* ignore annotation if it is not str/BaseType/dict
* update param name in the check_type functions
remove schema validators for GCRPath, and adjust for GCRPath, GCSPath
change _check_valid_dict to _check_valid_type_dict to avoid confusion
fix typo in the comments
adjust function order for readability
* remove default values for non-primitive types in the function signature
update the _check_valid_type_dict name
* pass metadata from component decorator and task factory to containerOp
* pass pipeline metadata to Pipeline
* fix unit test
* typo in the comments
* move the metadata classes to a separate module
* fix unit test
* small change
* add __eq__ to meta classes
not export _metadata classes
* nothing
* fix unit test
* unit test python component
* unit test python pipeline
* fix bug: duplicate variable of args
* fix unit tests
* move python_component and _component decorator in _component file
* remove the print
* change parameter default value to None
* add functools wraps around _component decorator
* TypeMeta accept both str and dict
* fix indent, add unit test for type as strings
* do not set default value for the name field in ParameterMeta, ComponentMeta, and PipelineMeta
* add type check in task factory
* output error message
* add type check in component decorator; move the metadata assignment out of the containerop __init__ function
* fix bug; add unit test
* add more unit tests
* more unit tests; fix bugs
* more unit tests; fix bugs
* add unit tests
* more unit tests
* add type check switch; add unit tests
* add compiler option for type check
* resolving pr comments
* add unit test for pipeline param check with component types; fix the bug; also fix the bug when there are not a single return annotations