code: def _parse_constant(self, exprnode, partial_length_ok=False):
      # for now, limited to expressions that are an immediate number
      # or positive/negative number
      if isinstance(exprnode, pycparser.c_ast.Constant):
          s = exprnode.value
          if "0" <= s[0] <= "9":
              s = s.rstrip("uUlL")
              try:
                  if s.startswith("0"):
                      return int(s, 8)
                  else:
                      return int(s, 10)
              except ValueError:
                  if len(s) > 1:
                      if s.lower()[0:2] == "0x":
                          return int(s, 16)
                      elif s.lower()[0:2] == "0b":
                          return int(s, 2)
              raise CDefError("invalid constant %r" % (s,))
          elif (
              s[0] == "'"
              and s[-1] == "'"
              and (len(s) == 3 or (len(s) == 4 and s[1] == "\\"))
          ):
              return ord(s[-2])
          else:
              raise CDefError("invalid constant %r" % (s,))
      #
      if (
          isinstance(exprnode, pycparser.c_ast.UnaryOp)
          and exprnode.op == "+"
      ):
          return self._parse_constant(exprnode.expr)
      #
      if (
          isinstance(exprnode, pycparser.c_ast.UnaryOp)
          and exprnode.op == "-"
      ):
          return -self._parse_constant(exprnode.expr)
      # load previously defined int constant
      if (
          isinstance(exprnode, pycparser.c_ast.ID)
          and exprnode.name in self._int_constants
      ):
          return self._int_constants[exprnode.name]
      #
      if (
          isinstance(exprnode, pycparser.c_ast.ID)
          and exprnode.name == "__dotdotdotarray__"
      ):
          if partial_length_ok:
              self._partial_length = True
              return "..."
          raise FFIError(
              ":%d: unsupported '[...]' here, cannot derive "
              "the actual array length in this context"
              % exprnode.coord.line
          )
      #
      if isinstance(exprnode, pycparser.c_ast.BinaryOp):
          left = self._parse_constant(exprnode.left)
          right = self._parse_constant(exprnode.right)
          if exprnode.op == "+":
              return left + right
          elif exprnode.op == "-":
              return left - right
          elif exprnode.op == "*":
              return left * right
          elif exprnode.op == "/":
              return self._c_div(left, right)
          elif exprnode.op == "%":
              return left - self._c_div(left, right) * right
          elif exprnode.op == "<<":
              return left << right
          elif exprnode.op == ">>":
              return left >> right
          elif exprnode.op == "&":
              return left & right
          elif exprnode.op == "|":
              return left | right
          elif exprnode.op == "^":
              return left ^ right
      #
      raise FFIError(
          ":%d: unsupported expression: expected a "
          "simple numeric constant" % exprnode.coord.line
      )
  
imports: from .None import model
  from .commontypes import COMMON_TYPES, resolve_common_type
  from .error import FFIError, CDefError
  import weakref, re, sys
label_desc: Use image node_id 22 for calling the Parser obj's underlying member method code with example usage: obj._parse_constant(exprnode, partial_length_ok) and returns: self, unknown, self, str, unknown, ord, unknown, int, int, unknown, self, int, unknown, int, unknown, unknown, unknown, unknown, unknown