'Add extensions to the request.
:param extensions: a sequence of X509Extension objects
:return: None'

def add_extensions(self, extensions):

    stack = _lib.sk_X509_EXTENSION_new_null()
    if (stack == _ffi.NULL):
        _raise_current_error()
    stack = _ffi.gc(stack, _lib.sk_X509_EXTENSION_free)
    for ext in extensions:
        if (not isinstance(ext, X509Extension)):
            raise ValueError('One    of    the    elements    is    not    an    X509Extension')
        _lib.sk_X509_EXTENSION_push(stack, ext._extension)
    add_result = _lib.X509_REQ_add_extensions(self._req, stack)
    if (not add_result):
        _raise_current_error()
