Functions/Public/Test-GitHubAssignee.ps1

function Test-GitHubAssignee {
    <#
    .Synopsis
    This function returns a boolean value, indicating whether or not a GitHub username is a valid assignee for the specified repository.

    .Link
    https://trevorsullivan.net
    https://developer.github.com/v3/issues/assignees/#check-assignee
    #>

    [CmdletBinding()]
    param (
        [Security.SecureString] $Token = (Get-GitHubToken)
    )

    $ApiCall = @{
        Body   = '';
        Uri    = '';
        Method = '';
        Token  = $Token
    }

    Invoke-GitHubApi @ApiCall;
}