'Displays all virtual interfaces for an AWS account. Virtual
interfaces deleted fewer than 15 minutes before
DescribeVirtualInterfaces is called are also returned. If a
connection ID is included then only virtual interfaces
associated with this connection will be returned. If a virtual
interface ID is included then only a single virtual interface
will be returned.
A virtual interface (VLAN) transmits the traffic between the
AWS Direct Connect location and the customer.
If a connection ID is provided, only virtual interfaces
provisioned on the specified connection will be returned. If a
virtual interface ID is provided, only this particular virtual
interface will be returned.
:type connection_id: string
:param connection_id: ID of the connection.
Example: dxcon-fg5678gh
Default: None
:type virtual_interface_id: string
:param virtual_interface_id: ID of the virtual interface.
Example: dxvif-123dfg56
Default: None'

def describe_virtual_interfaces(self, connection_id=None, virtual_interface_id=None):

    params = {}
    if (connection_id is not None):
        params['connectionId'] = connection_id
    if (virtual_interface_id is not None):
        params['virtualInterfaceId'] = virtual_interface_id
    return self.make_request(action='DescribeVirtualInterfaces', body=json.dumps(params))
