Try to find out what type of variants that exists in a variant source
    
        Args:
            variant_source (str): Path to variant source
            source_mode (str): 'vcf' or 'gemini'
        
        Returns:
            variant_type (str): 'sv' or 'snv'

def get_variant_type(variant_source):
    """Try to find out what type of variants that exists in a variant source
    
        Args:
            variant_source (str): Path to variant source
            source_mode (str): 'vcf' or 'gemini'
        
        Returns:
            variant_type (str): 'sv' or 'snv'
    """
    file_type = get_file_type(variant_source)
    variant_type = 'sv'
    if file_type == 'vcf':
        variants = VCF(variant_source)
    elif file_type == 'gemini':
        variants = GeminiQuery(variant_source)
        gemini_query = "SELECT * from variants"
        variants.run(gemini_query)
    # Check 1000 first variants, if anyone is a snv we set the variant_type
    # to 'snv'
    for i,variant in enumerate(variants):
        if file_type == 'vcf':
            if variant.is_snp:
                variant_type = 'snv'
        elif file_type == 'gemini':
            if variant['type'] == 'snp':
                variant_type = 'snv'
            
        if i > 1000:
            break
    
    return variant_type