This function performs k-nearest neighbor based smoothing imputation
on a gene expression matrix.
     
    
    Usage
    RunKNNSmooth(data_mat, k = 15, verbose = TRUE)
 
    
    Arguments
- data_mat
- Expression matrix with genes as rows and cells as columns 
- k
- Number of nearest neighbors (default: 15) 
- verbose
- Print progress messages 
 
    
    Value
    Imputed expression matrix