mmg_toolbox tests fail for evaluation

[DanPorter]

Running tests against the latests version of HdfMap fail:

Test

https://github.com/DiamondLightSource/mmg_toolbox/blob/49f5b2482320953d326890ca6026a2b35257d72c/tests/test_nexus_scan.py#L23

    f = DIR + '/i16/1109527.nxs'
    scan = NexusScan(f)
    ...
    assert scan('max(signal / Transmission / (rc/300.) / _t)') == approx(1215483134.5953412)

Error

Traceback (most recent call last):
  File "<input>", line 1, in <module>
  File "/scratch/grp66007/python/hdfmap/src/hdfmap/hdfmap_class.py", line 1086, in eval
    return eval_hdf(
        hdf_file=hdf_file,
    ...<6 lines>...
        raise_errors=raise_errors
    )
  File "/scratch/grp66007/python/hdfmap/src/hdfmap/eval_functions.py", line 483, in eval_hdf
    expression = prepare_expression_load_data(hdf_file, expression, hdf_namespace, data_namespace,
                                              replace_names, default, use_stored_data)
  File "/scratch/grp66007/python/hdfmap/src/hdfmap/eval_functions.py", line 433, in prepare_expression_load_data
    identifiers = find_identifiers(expression)
  File "/scratch/grp66007/python/hdfmap/src/hdfmap/eval_functions.py", line 239, in find_identifiers
    return [name for name in asteval.get_ast_names(ast.parse(expression))]
                                                   ~~~~~~~~~^^^^^^^^^^^^
  File "/dls/science/users/grp66007/.local/share/uv/python/cpython-3.14.5-linux-x86_64-gnu/lib/python3.14/ast.py", line 46, in parse
    return compile(source, filename, mode, flags,
                   _feature_version=feature_version, optimize=optimize)
  File "<unknown>", line 1
    max(signal / Transmission / (rc/300.) / count_time
       ^
SyntaxError: '(' was never closed

[DanPorter]

The cause appears to be the _t alternate name as the expression works fine without this:

import hdfmap
m = hdfmap.create_nexus_map('/i16/1109527.nxs')
m.eval(m.load_hdf(), 'max(signal / Transmission / (rc/300.))')

Completes. But

import hdfmap
m = hdfmap.create_nexus_map('/i16/1109527.nxs')
m.eval(m.load_hdf(), 'max(_t)')

Gives the error above.

Likely due to the change in regex in a4d0732