lib/index.js
function setIn(record, accessor, value, ctx) {
    return mutate(record, accessor, MutateType.setIn, value, ctx);
}
function setIn(record, accessor, value, ctx) {
    return mutate(record, accessor, MutateType.setIn, value, ctx);
}
function setIn ( record , accessor , value , ctx ) { return mutate ( record , accessor , MutateType . setIn , value , ctx ) ; }
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@param record The object to update, it can be a plain object or a class instance
@param accessor A lambda function to get the key path, support dot, [''], [""], [1], **do not** support dynamic variable, function call, e.g.
@param value The new value to set, if it is ignored it will be set to undefined.
@param ctx Dynamic key map.
Set a deep child