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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _string_to_int(s, state, region, base, signed, read_length=None):
 """ reads values from s and generates the symbolic number that it would equal the first char is either a number in the given base, or the result is 0 expression indicates whether or not it was successful """


        # if length wasn't provided, read the maximum bytes
        length = state.libc.max_strtol_len if read_length is None else read_length

        # expression whether or not it was valid at all
        expression, _ = strtol._char_to_val(region.load(s, 1), base)

        cases = []

        # to detect overflows we keep it in a larger bv and extract it at the end
        num_bits = min(state.arch.bits*2, 128)
        current_val = state.solver.BVV(0, num_bits)
        num_bytes = state.solver.BVS("num_bytes", state.arch.bits)
        constraints_num_bytes = []
        conditions = []

        cutoff = False
        # we need all the conditions to hold except the last one to have found a value
        for i in range(length):
            char = region.load(s + i, 1)
            condition, value = strtol._char_to_val(char, base)

            # if it was the end we'll get the current val
            cases.append((num_bytes == i, current_val))

            # identify the constraints necessary to set num_bytes to the current value
            # the current char (i.e. the terminator if this is satisfied) should not be a char,
            # so `condition` should be false, plus all the previous conditions should be satisfied
            case_constraints = conditions + [state.solver.Not(condition)] + [num_bytes == i]
            constraints_num_bytes.append(state.solver.And(*case_constraints))

            # break the loop early if no value past this is viable
            if condition.is_false():
                cutoff = True  # ???
                break

            # add the value and the condition
            current_val = current_val*base + value.zero_extend(num_bits-8)
            conditions.append(condition)

        # the last one is unterminated, let's ignore it
        if not cutoff:
            cases.append((num_bytes == length, current_val))
            case_constraints = conditions + [num_bytes == length]
            constraints_num_bytes.append(state.solver.And(*case_constraints))

        # only one of the constraints need to hold
        # since the constraints look like (num_bytes == 2 and the first 2 chars are valid, and the 3rd isn't)

        final_constraint = state.solver.Or(*constraints_num_bytes)
        if final_constraint.op == '__eq__' and final_constraint.args[0] is num_bytes and not final_constraint.args[1].symbolic:
            # CONCRETE CASE
            result = cases[state.solver.eval(final_constraint.args[1])][1]
            num_bytes = final_constraint.args[1]
        else:
            # symbolic case
            state.add_constraints(final_constraint)
            result = state.solver.ite_cases(cases, 0)

        # overflow check
        max_bits = state.arch.bits-1 if signed else state.arch.bits
        max_val = 2**max_bits - 1
        result = state.solver.If(result < max_val, state.solver.Extract(state.arch.bits-1, 0, result),
                             state.solver.BVV(max_val, state.arch.bits))

        return expression, result, num_bytes