def solve_one(self, expr, constrain=False):
expr = self.migrate_expression(expr)<EOL>value = self._solver.get_value(self._constraints, expr)<EOL>if constrain:<EOL><INDENT>self.constrain(expr == value)<EOL><DEDENT>if isinstance(value, bytearray):<EOL><INDENT>value = bytes(value)<EOL><DEDENT>return value<EOL>
Concretize a symbolic :class:`~manticore.core.smtlib.expression.Expression` into
one solution.

:param manticore.core.smtlib.Expression expr: Symbolic value to concretize
:param bool constrain: If True, constrain expr to concretized value
:return: Concrete value
:rtype: int