I can't understand what mistake I had done, about boundary marker

General
1

TypeError Traceback (most recent call last)
in
42 boundary_markers=MeshFunction(‘size_t’,mesh,mesh.topology().dim()-1)
43 #标记边界
—> 44 bx0.mark(boundary_markers,0)
45 bx1.mark(boundary_markers,1)
46 #定义边界条件

TypeError: mark(): incompatible function arguments. The following argument types are supported:
1. (self: dolfin.cpp.mesh.SubDomain, meshfunction: dolfin.cpp.mesh.MeshFunctionSizet, marker: int, check_midpoint: bool = True) → None
2. (self: dolfin.cpp.mesh.SubDomain, meshfunction: dolfin.cpp.mesh.MeshFunctionDouble, marker: float, check_midpoint: bool = True) → None
3. (self: dolfin.cpp.mesh.SubDomain, meshfunction: dolfin.cpp.mesh.MeshFunctionBool, marker: bool, check_midpoint: bool = True) → None

Invoked with: <dolfin.cpp.mesh.MeshFunctionSizet object at 0x7f757ba8d998>, 0

2

Please provide a minimal reproducible example.
It is unclear what bx0 and bx1 ins in your case.