diff --git a/source/_static/code/amplicon_len.py b/source/_static/code/amplicon_len.py
new file mode 100644
index 0000000000000000000000000000000000000000..3e9eeea9b3c222681fdaacefd7ac6119212f5d04
--- /dev/null
+++ b/source/_static/code/amplicon_len.py
@@ -0,0 +1,15 @@
+
+def amplicon_len(seq, primer_1, primer_2):
+    """
+    given primer_1 and primer_2 
+    return the lenght of the amplicon
+    primer_1 and primer_2 ar present and in this order 
+    in sequence 
+    """
+    primer_1 = primer_1.upper()
+    primer_2 = primer_2.upper()
+    sequence = sequence.upper()
+    pos_1 = sv40_sequence.find(primer_1)
+    pos_2 = sv40_sequence.find(primer_2)
+    amplicon_len = pos_2 + len(primer_2) - pos_1
+    return amplicon_len
\ No newline at end of file
diff --git a/source/_static/code/fasta_to_one_line.py b/source/_static/code/fasta_to_one_line.py
new file mode 100644
index 0000000000000000000000000000000000000000..6ef59c05b921f85ff9fe6886321b83a0f696008e
--- /dev/null
+++ b/source/_static/code/fasta_to_one_line.py
@@ -0,0 +1,7 @@
+
+def fasta_2_one_line(seq):
+    header_end_at = find('\n')
+    seq = seq[:header_end_at + 1]
+    seq = seq.replace('\n', '')
+    return seq
+
diff --git a/source/_static/code/gc_percent.py b/source/_static/code/gc_percent.py
new file mode 100644
index 0000000000000000000000000000000000000000..b5d988b99343fa3fdb6eabd2b8c5ce9aec539607
--- /dev/null
+++ b/source/_static/code/gc_percent.py
@@ -0,0 +1,4 @@
+
+def gc_percent(seq):
+    gc_pc =  float(seq.count('g') + seq.count('c')) / float(len(seq))
+    return gc_pc
\ No newline at end of file
diff --git a/source/_static/code/vol_of_sphere.py b/source/_static/code/vol_of_sphere.py
new file mode 100644
index 0000000000000000000000000000000000000000..72884956851f2ce1d5bee95928c00646380d560d
--- /dev/null
+++ b/source/_static/code/vol_of_sphere.py
@@ -0,0 +1,9 @@
+import math
+
+def vol_of_sphere(radius):
+    """
+    compute the volume of sphere of a given radius
+    """
+    
+    vol = float(4)/float(3) * float(math.pi) * pow(radius, 3)
+    return vol