<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def check(requirements_paths=[], metadata=[], projects=[]):
 """Return True if all of the specified dependencies have been ported to Python 3. The requirements_paths argument takes a sequence of file paths to requirements files. The 'metadata' argument takes a sequence of strings representing metadata. The 'projects' argument takes a sequence of project names. Any project that is not listed on PyPI will be considered ported. """

    dependencies = []
    dependencies.extend(projects_.projects_from_requirements(requirements_paths))
    dependencies.extend(projects_.projects_from_metadata(metadata))
    dependencies.extend(projects)

    manual_overrides = pypi.manual_overrides()

    for dependency in dependencies:
        if dependency in manual_overrides:
            continue
        elif not pypi.supports_py3(dependency):
            return False
    return True