Calling bespoke function from another workbook

[BuddJ]

I have the two functions shown below in a workbook along with several macros - the idea is that all macros, etc. are stored in a single file / workbook / location but run across several workbooks as / when required.

Calling the macro's is easy enough, but how do I "execute" the functions in a workbook different to the one that they are saved in ?? Note one function references the other ..........

Many thanks

Function GetCellColor(xlRange As Range)
    Dim indRow, indColumn As Long
    Dim arResults()
 
    Application.Volatile
 
    If xlRange Is Nothing Then
        Set xlRange = Application.ThisCell
    End If
 
    If xlRange.Count > 1 Then
      ReDim arResults(1 To xlRange.Rows.Count, 1 To xlRange.Columns.Count)
       For indRow = 1 To xlRange.Rows.Count
         For indColumn = 1 To xlRange.Columns.Count
           arResults(indRow, indColumn) = xlRange(indRow, indColumn).Interior.Color
         Next
       Next
     GetCellColor = arResults
    Else
     GetCellColor = xlRange.Interior.Color
    End If
End Function
 
 
Function CountCellsByColor(rData As Range, cellRefColor As Range) As Long
    Dim indRefColor As Long
    Dim cellCurrent As Range
    Dim cntRes As Long
 
    Application.Volatile
    cntRes = 0
    indRefColor = cellRefColor.Cells(1, 1).Interior.Color
    For Each cellCurrent In rData
        If indRefColor = cellCurrent.Interior.Color Then
            cntRes = cntRes + 1
        End If
    Next cellCurrent
 
    CountCellsByColor = cntRes
End Function