Returns true if the variable is a single trajectory feature

    :param netCDF4.Dataset nc: An open netCDF dataset
    :param str variable: name of the variable to check

def is_single_trajectory(nc, variable):
    '''
    Returns true if the variable is a single trajectory feature

    :param netCDF4.Dataset nc: An open netCDF dataset
    :param str variable: name of the variable to check
    '''
    # x(t), y(t), z(t), t(t)
    # X(t)
    dims = nc.variables[variable].dimensions
    cmatrix = coordinate_dimension_matrix(nc)

    for req in ('x', 'y', 't'):
        if req not in cmatrix:
            return False
    t = get_time_variable(nc)
    if cmatrix['x'] != (t,):
        return False
    if cmatrix['x'] != cmatrix['y']:
        return False
    if cmatrix['x'] != cmatrix['t']:
        return False
    if 'z' in cmatrix and cmatrix['x'] != cmatrix['z']:
        return False
    if dims == cmatrix['x']:
        return True
    return False