### util.existential
> Functions which deal with whether a value “exists.”
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#### exists
**Signature:** `_.exists(value:Any)`
Checks whether or not the value is “existy.” Both `null` and `undefined` are
considered non-existy values. All other values are existy.
“`javascript
_.exists(null);
// => false
_.exists(undefined);
// => false
_.exists({});
// = > true
_.exists(“Sparta”);
// => true
“`
——————————————————————————–
#### falsey
**Signature:** `_.falsey(value:Any)`
Checks whether the value is falsey. A falsey value is one which coerces to
`false` in a boolean context.
“`javascript
_.falsey(0);
// => true
_.falsey(“”);
// => true
_.falsey({});
// => false
_.falsey(“Corinth”);
// => false
“`
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#### firstExisting
**Signature:** `_.firstExisting(value:Any[, value:Any…])`
Returns the first existy argument from the argument list.
“`javascript
_.firstExisting(“Socrates”, “Plato”);
// => “Socrates”
_.firstExisting(null, undefined, “Heraclitus”);
// => “Heraclitus”
“`
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#### not
**Signature:** `_.not(value:Any)`
Returns a boolean which is the opposite of the truthiness of the original value.
“`javascript
_.not(0);
// => true
_.not(1);
// => false
_.not(true);
// => false
_.not(false);
// => true
_.not({});
// => false
_.not(null);
// => true
“`
——————————————————————————–
#### truthy
**Signature:** `_.truthy(value:Any)`
Checks whether the value is truthy. A truthy value is one which coerces to
`true` in a boolean context.
“`javascript
_.truthy({});
// => true
_.truthy(“Athens”);
// => true
_.truthy(0);
// => false
_.truthy(“”);
// => false
“`
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