checking standard equality, the function returns its index.</p>
<p>If <code>x</code> is not found, the function returns -1.</p>
<p>If <code>fromIndex</code> is specified, it will be used as the starting index to search from,
otherwise search starts with the last element index. If it is negative, it will be
taken as the offset from the end of <code>this</code> Array to compute the starting index. If
given or computed starting index is greater than or equal to the length of <code>this</code> Array,
the whole 