<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_build_container_dir(self, arch):
        '''Given the arch name, returns the directory where it will be
        built.

        This returns a different directory depending on what
        alternative or optional dependencies are being built.
        '''
        dir_name = self.get_dir_name()
        return join(self.ctx.build_dir, 'other_builds',
                    dir_name, '{}__ndk_target_{}'.format(arch, self.ctx.ndk_api))