python markdown to html

# Markdown to html
import re

a = 'D:/Markdown/a.txt'
file = open(a,'r')
lines = file.read()
file.close()

lines = '\n'+lines+'\n'

def blockQuote(lines):
    lines = re.sub('(\n>){1,}','\n>',lines)
    #lines = re.sub(r'(\n>)','\n>',lines)
    lines1 = re.split(r'(\n>)',lines)
    lines2=''
    for idx, elem in enumerate(lines1):
        #if previous element is \n> then append it,
        #if previous element is \n> and next element is not \n> then append block code
        #else append with nothing
        if lines1[idx]=='\n>':
            lines2=lines2
        elif lines1[idx-1]!='\n>':
            if idx != len(lines1)-1:
                if lines1[idx+1]=='\n>':
                    lines2=lines2+str(elem)+'\n<blockquote>'
                else:
                    lines2=lines2+str(elem)
            else:
                lines2=lines2+str(elem)
        elif lines1[idx-1] == '\n>':
            if idx != len(lines1)-1:
                if lines1[idx+1] != '\n>':
                    lines2 = lines2 + re.sub(r'(?=\n)',r''+'\n</blockquote>',elem,count =1)
                else:
                    lines2=lines2+'\n>'+str(elem)
            else:
                lines2 = lines2 +'\n>'+re.sub(r'(?=\n)',r''+'\n</blockquote>',elem,count =1)
    return lines2

def header(lines):
    for x in reversed(range(1,6)): # headers only work from 1 to 6
        lines = re.sub(r'(?<=\n)(?:[#]{'+str(x)+'}\s)([^\n]+)',r'\1'+'</h'+str(x)+'>\n',lines)
        lines = re.sub(r'(?<=\n)(?:(?:> )[#]{'+str(x)+'}\s)([^\n]+)',r'> \1'+'</h'+str(x)+'>\n',lines) #for block quotes
        lines = re.sub(r'([\s#]+)(</h[1-6]?)',r'\2',lines)
    lines = re.sub(r'\n[=]+\n',r'</h1>\n',lines)
    lines = re.sub(r'\n[-]+\n',r'</h2>\n',lines)
    for x in reversed(range(1,6)): #add the h tags to the beginning of the line
        lines = re.sub(r'(?<=\n)(?=[^\n]+</h'+str(x)+'>)',r'<h'+str(x)+'>',lines)
    return lines

def paragraph(lines):
    lines = re.sub(r'(<[hH][1-6]>)>\s+',r'\1',lines)
    lines = re.sub(r'\n>','\n<p>',lines)
    lines = re.sub(r'(?<=\n\n)(?=[^><\s])','<p>',lines)
    lines = re.sub(r'([\n]{3,})','\n\n',lines)
    lines = re.sub(r'(?<=[^>])(?=\n\n)',r'</p>',lines)
    return lines

def emphasis(lines):
    lines = re.sub(r'\*{2}([^\n]+)\*{2}',r'<strong>\1</strong>',lines)
    lines = re.sub(r'_{2}([^\n]+)_{2}',r'<strong>\1</strong>',lines)
    lines = re.sub(r'[\*_]([^\n]+)[\*_]',r'<b>\1</b>',lines)
    return lines

def List(lines):
    lines1 = re.split(r'(\n[0-9]+\.)',lines)
    #get the indices for 1.
    b = [elem for elem in range(len(lines1)) if lines1[elem]=='\n1.']
    lines2 = lines1

    for elem in b:
        lines2[elem] = '\n\n<ol>\n<li>'
        i = 1
        dummy = str(i+1)
        index = min(elem+2,len(lines2)-1)
        while (dummy==str(i+1)):
            index = min(index,len(lines2)-1)
            dummy = re.sub(r'\n([0-9]+)\.',r'\1',lines2[index])
            if dummy==str(i+1):
                lines2[index] = '\n<li>'
                i+=1
                dummy = str(i+1)
                index += 2
    lines3 = ''
    for elem in lines2:
        lines3 = lines3 + elem
    lines3 = re.sub(r'(<li>[^\n]+)(?=\n)',r'\1</li>',lines3)
    lines3 = re.sub(r'(</li>\n)(?=[^<])',r'\1</ol>\n\n',lines3)
    lines3 = re.sub(r'(?<=\n)([\*+-])',r'<li>\1',lines3)
    lines3 = re.sub(r'(<li>[\*+-][^\n]+)(?=\n)',r'\1</li>',lines3)
    lines3 = re.sub(r'(<li>[\*+-][\s]+)','<li>',lines3)
    return lines3

lines = List(lines)
lines = emphasis(lines)
lines = blockQuote(lines)
lines = header(lines)
lines = paragraph(lines)

f = open("D:/test1.html","w")
f.write(lines)
f.close()