@solve.implementation(for_type=ast.Let)<EOL>def solve_let(expr, vars):
lhs_value = solve(expr.lhs, vars).value<EOL>if not isinstance(lhs_value, structured.IStructured):<EOL><INDENT>raise errors.EfilterTypeError(<EOL>root=expr.lhs, query=expr.original,<EOL>message="<STR_LIT>"<EOL>% (lhs_value,))<EOL><DEDENT>return solve(expr.rhs, __nest_scope(expr.lhs, vars, lhs_value))<EOL>
Solves a let-form by calling RHS with nested scope.