def html_body_id(request):
    """
    Assign a variable name 'html_body_id' to the context.
    html_body_id value is computed from request.path.
    It corresponds to the first part of request.path.
    If request.path is '/', then 'home' is used as id.
    """
    path_parts = request.path.split('/')
    i = 0
    while i < len(path_parts) and path_parts[i] == '':
        i += 1
    if i < len(path_parts):
        body_id = path_parts[i]
    else:
        body_id = 'home'
    return {'html_body_id': body_id}
