# 
## Overview
In Ruby, the **`hash.key?()`** method is used to check if a given key exists in a hash. 

## Syntax
```ruby
hash.key?(keyToFind)
```
## Parameters
This method takes **`keyToFind`** as a parameter. It is the key we want to check.

## Return value
It returns a `boolean` value. It returns `true` if the key exists. Otherwise, it returns `false`.

## Example



# create hashes
h1 = {one: 1, two: 2, three: 3}
h2 = {name: "okwudili", stack: "ruby"}
h3 = {"foo": 0, "bar": 1}
h4 = {M:"Mango", A: "Apple", B: "Banana"}

# check if key exists 
# and print results
puts h1.key?(:one)
puts h2.key?(:name)
puts h3.key?(:foo)
puts h4.key?(:C)

## Explanation
* **Lines 2–5**: We create some hashes.

* **Lines 9–12**: We check if some keys exist in the hashes. Next, we print the results to the console.

What is the hash.key?() method in Ruby?

Used in Ruby to check if a given key exists in a hash, returning true or false.