<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_default_gwf_api():
 """Return the preferred GWF library Examples -------- If you have |LDAStools.frameCPP|_ installed: 'framecpp' Or, if you don't have |lalframe|_: 'lalframe' Otherwise: ImportError: no GWF API available, please install a third-party GWF library (framecpp, lalframe) and try again """

    for lib in APIS:
        try:
            import_gwf_library(lib)
        except ImportError:
            continue
        else:
            return lib
    raise ImportError("no GWF API available, please install a third-party GWF "
                      "library ({}) and try again".format(', '.join(APIS)))