tex font cannot be used in matplotlib after import pyOPAL

There seems to be an issue with adding tex symbols in matplotlib after import pyOPAL. The simple code snippet below

from matplotlib import rc
from opal.opal import load_dataset
import matplotlib.pyplot as plt

FontSize=22
FontSizeLabelAxis=22
rc('xtick',labelsize=FontSize)
rc('ytick',labelsize=FontSize)
rc('text', usetex=True)

x=np.linspace(-10,10,100)
plt.plot (x,x**2)
plt.xlabel (r'$x$ ')

give the error

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-4-11cccf49f543> in <module>
     14 x=np.linspace(-10,10,100)
     15 plt.plot (x,x**2)
---> 16 plt.xlabel (r'$x$ ')

/usr/lib64/python3.9/site-packages/matplotlib/pyplot.py in xlabel(xlabel, fontdict, labelpad, loc, **kwargs)
   3113 @_copy_docstring_and_deprecators(Axes.set_xlabel)
   3114 def xlabel(xlabel, fontdict=None, labelpad=None, *, loc=None, **kwargs):
-> 3115     return gca().set_xlabel(
   3116         xlabel, fontdict=fontdict, labelpad=labelpad, loc=loc,
   3117         **kwargs)

/usr/lib64/python3.9/site-packages/matplotlib/axes/_axes.py in set_xlabel(self, xlabel, fontdict, labelpad, loc, **kwargs)
    245         elif loc == 'right':
    246             kwargs.update(x=1, horizontalalignment='right')
--> 247         return self.xaxis.set_label_text(xlabel, fontdict, **kwargs)
    248 
    249     def get_ylabel(self):

/usr/local/lib/python3.9/site-packages/opal-1.0.0-py3.9.egg/opal/utilities/wrapper.py in run(*args, **kwargs)
     35     @functools.wraps(fun)
     36     def run(*args, **kwargs):
---> 37         return new_fun(fun, *args, **kwargs)
     38     return run
     39 

/usr/local/lib/python3.9/site-packages/opal-1.0.0-py3.9.egg/opal/utilities/wrapper.py in new_label(fun, *args, **kwargs)
     67         # we need to add the signs otherwise LaTex formulas
     68         # are not properly compiled
---> 69         re._alphanum_str = re._alphanum_str.union(signs)
     70         lst[idx] = re.escape(lst[idx])
     71         # remove signs again

AttributeError: module 're' has no attribute '_alphanum_str'