>>> arr = ndtest('axis1=x1..x3;axis2=x1..x3')
>>> arr.insert(arr['axis1[x1,x2]'], before='axis1[x3]')
ValueError: ['x1'] is ambiguous (valid in axis1, axis2)
>>> # it works if the values has not the axis
>>> arr.insert(arr['axis1[x1]'], before='axis1[x3]', label='x1')
axis1\axis2 x1 x2 x3
x1 0 1 2
x2 3 4 5
x1 0 1 2
x3 6 7 8
>>> # it works if the labels are not ambiguous
>>> arr2 = arr.set_labels('axis2', str.upper)
>>> arr2.insert(arr2['axis1[x2,x1]'], before='axis1[x3]')
axis1\axis2 X1 X2 X3
x1 0 1 2
x2 3 4 5
x2 3 4 5
x1 0 1 2
x3 6 7 8
