code: def get_surface_equilibrium(self, slab_entries, delu_dict=None):
  
          
          # Generate all possible coefficients
          all_parameters = []
          all_eqns = []
          for slab_entry in slab_entries:
              se = self.surfe_dict[slab_entry]
  
              # remove the free chempots we wish to keep constant and
              # set the equation to 0 (subtract gamma from both sides)
              if type(se).__name__ == "float":
                  all_eqns.append(se - Symbol("gamma"))
              else:
  
                  se = sub_chempots(se, delu_dict) if delu_dict else se
                  all_eqns.append(se - Symbol("gamma"))
                  all_parameters.extend([p for p in list(se.free_symbols)
                                         if p not in all_parameters])
  
          all_parameters.append(Symbol("gamma"))
          # Now solve the system of linear eqns to find the chempot
          # where the slabs are at equilibrium with each other
  
          soln = linsolve(all_eqns, all_parameters)
          if not soln:
              warnings.warn("No solution")
              return soln
          return {p: list(soln)[0][i] for i, p in enumerate(all_parameters)}
docs: Takes in a list of SlabEntries and calculates the chemical potentials
              at which all slabs in the list coexists simultaneously. Useful for
              building surface phase diagrams. Note that to solve for x equations
              (x slab_entries), there must be x free variables (chemical potentials).
              Adjust delu_dict as need be to get the correct number of free variables.
          Args:
              slab_entries (array): The coefficients of the first equation
              delu_dict (Dict): Dictionary of the chemical potentials to be set as
                  constant. Note the key should be a sympy Symbol object of the
                  format: Symbol("delu_el") where el is the name of the element.
  
          Returns:
              (array): Array containing a solution to x equations with x
                  variables (x-1 chemical potential and 1 surface energy)